Preserve Exact Body Bytes

@exclude-18

Some HTTP servers are not well-behaved and respond with invalid data: the response body may
not be encoded according to the encoding specified in the HTTP headers, or there may be bytes
that are invalid for the given encoding. The YAML and JSON serializers are not generally
designed to handle these cases gracefully, and you may get errors when the cassette is serialized
or deserialized. Also, the encoding may not be preserved when round-tripped through the
serializer.

VCR provides a configuration option to deal with cases like these. The preserve_exact_body_bytes
method accepts a block that VCR will use to determine if the body of the given request or response object
should be base64 encoded in order to preserve the bytes exactly as-is. VCR does not do this by
default, since base64-encoding the string removes the human readibility of the cassette.

Alternately, if you want to force an entire cassette to preserve the exact body bytes,
you can pass the :preserve_exact_body_bytes => true cassette option when inserting your
cassette.